Network Programming with Python. Sébastien Tixeuil

Transcription

1 Network Programming with Python Sébastien Tixeuil

2 Python 101

3 Python Standard Types Numbers: 1, 122L, 2.0, 1e+2j Strings: Python, PROGRES Lists: [123, ABC ] Tuples: (123, ABC ) Dictionaries: { num : 123, str : ABC }

4 Python Subscripting str = "PROGRES" print(str[2:4]) print(str[2:]) print(str[-1:]) l = [1,2,3,4,5] print(l[2:4]) print(l[2:]) print(l[-1:])

5 Python Subscripting str = "PROGRES" print(str[2:4]) print(str[2:]) print(str[-1:]) l = [1,2,3,4,5] print(l[2:4]) print(l[2:]) print(l[-1:]) OG OGRES S [3, 4] [3, 4, 5] [5]

6 Python Operators Arithmetic: +,-,*,/,%,**,// Comparison: ==,!=,<>,>,<,>=,<= Assignment: =,+=,-=,*=,/=,%=,**=,//= Logical: and, or, not Bitwise: &,,~,<<,>> Membership: in, not in Identity: is, is not

7 Python Conditions var1 = 100 if var1: print ("1 - Got a true expression value") print (var1) else: print ("1 - Got a false expression value") print (var1) var2 = 0 if var2: print ("2 - Got a true expression value") print (var2) else: print ("2 - Got a false expression value") print (var2) print ("Good bye!")

8 Python Conditions var1 = 100 if var1: print ("1 - Got a true expression value") print (var1) else: print ("1 - Got a false expression value") print (var1) var2 = Got a true expression value Got a false expression value if var2: print ("2 - Got a true expression value") print (var2) else: print ("2 - Got a false expression value") print (var2) 0 Good bye! print ("Good bye!")

9 Python While Loop count = 0 while (count < 9): print ('The count is:', count) count = count + 1 print ("Good bye!")

10 Python While Loop count = 0 while (count < 9): print ('The count is:', count) count = count + 1 print ("Good bye!") The count is: 0 The count is: 1 The count is: 2 The count is: 3 The count is: 4 The count is: 5 The count is: 6 The count is: 7 The count is: 8 Good bye!

11 Python For Loop for letter in 'Python': print ('Current Letter :', letter) fruits = ['banana', 'apple', 'mango'] for fruit in fruits: print ('Current fruit :', fruit) fruits = ['banana', 'apple', 'mango'] for index in range(len(fruits)): print ('Current fruit :', fruits[index])

12 Python For Loop for letter in 'Python': print ('Current Letter :', letter) fruits = ['banana', 'apple', 'mango'] for fruit in fruits: print ('Current fruit :', fruit) fruits = ['banana', 'apple', 'mango'] for index in range(len(fruits)): Current Letter : P Current Letter : y Current Letter : t Current Letter : h Current Letter : o Current Letter : n Current fruit : banana Current fruit : apple Current fruit : mango Current fruit : banana Current fruit : apple Current fruit : mango print ('Current fruit :', fruits[index])

13 Python Exceptions try: // dangerous code except ExceptionName: // code to handle the problem related // to the ExceptionName event

14 Python Exceptions from sys import * try: f = open('myfile.txt') s = f.readline() i = int(s.strip()) except OSError as err: print("os error: {0}".format(err)) except ValueError: print("could not convert data to an integer.") except: print("unexpected error:", sys.exc_info()[0]) raise

15 Python Exceptions try: raise Exception('prog','res') except Exception as inst: print(type(inst)) print(inst.args) print(inst) x, y = inst.args print('x =', x) print('y =', y)

16 Python Exceptions try: raise Exception('prog','res') except Exception as inst: print(type(inst)) print(inst.args) print(inst) x, y = inst.args <class Exception'> ('prog', res') ('prog', res') x = prog y = res print('x =', x) print('y =', y)

17 Python Functions def sum(arg1,arg2): res = arg1+arg2 return res print(sum(2,2))

18 Python Functions def sum(arg1,arg2): res = arg1+arg2 return res print(sum(2,2)) 4

19 Python Functions res=0 def sum(arg1,arg2): res = arg1+arg2 return res print(sum(2,2)) print(res)

20 Python Functions res=0 def sum(arg1,arg2): res = arg1+arg2 return res print(sum(2,2)) print(res) 4 0

21 Python Modules myfuncs.py def add(arg1,arg2): return arg1+arg2 usemyfuncs.py import myfuncs print(myfuncs.add(2,2))

22 Python Modules myfuncs.py def add(arg1,arg2): return arg1+arg2 usemyfuncs.py from myfuncs import * print(add(2,2))

23 Client-Server

24 Addressing Client Server A.B.C.D W.X.Y.Z

25 Addressing Client Server Process 1 Process 1 Process 2 Process 2 A.B.C.D W.X.Y.Z

26 Client-Server Client Process 1 Process 2 Server Service 1 port: 1234 Service 2 port: 4567 A.B.C.D W.X.Y.Z

27 Client-Server Two processes, client and server, are executed on (possibly) different machines The server awaits connections and provides a service The client connects to the server to request a service A particular process can be both client and server (possibly) for different services

28 UDP Sockets

29 UDP Sockets Client Server Client Socket port: 5678 UDP Datagrams Server Socket port: 1234 A.B.C.D W.X.Y.Z

30 UDP Client-Server Server Process Client Process Create & Bind Socket Create Socket Read Datagram Create, Send Datagram Send Response Datagram Read Datagram Close Socket

31 UDP Client-Server W.X.Y.Z:1234 A.B.C.D:5678 Create & Bind Socket port: 1234 Create Socket Read Datagram A.B.C.D:5678 W.X.Y.Z:1234 A.B.C.D:5678 Create, Send Datagram W.X.Y.Z:1234 Send Response Datagram A.B.C.D:5678 A.B.C.D:5678 W.X.Y.Z:1234 Read Datagram Close Socket

32 UDP Python Client from socket import * servername = A.B.C.D serverport = 1234 clientsocket = socket(af_inet,sock_dgram) message = input( lowercase sentence: ) clientsocket.sendto(message,(servername,serverport)) modifiedmessage, serveraddress = clientsocket.recvfrom(2048) print(modifiedmessage) clientsocket.close()

33 UDP Python Server from socket import * serverport = 1234 serversocket = socket(af_inet,sock_dgram) serversocket.bind((,serverport)) print( server ready ) while True: message, clientaddress = serversocket.recvfrom(2048) modifiedmessage = message.upper() serversocket.sendto(modifiedmessage,clientaddress)

34 UDP Client-Server W.X.Y.Z:1234 A.B.C.D:5678 Create & Bind Socket port: 1234 socket, bind Create Socket socket Read Datagram A.B.C.D:5678 recvfrom W.X.Y.Z:1234 A.B.C.D:5678 Create, Send Datagram W.X.Y.Z:1234 sendto Send Response Datagram A.B.C.D:5678 sendto A.B.C.D:5678 W.X.Y.Z:1234 Read Datagram recvfrom Close Socket close

35 TCP Sockets

36 TCP Sockets Client Client Socket port: 5678 TCP Handshake Bytes Server Server Socket port: 1234 Connection Socket port: 1234 A.B.C.D W.X.Y.Z

37 TCP Client-Server Server Process Client Process Create & Bind Server Socket Create Socket Wait for Incoming Connection on Server Socket TCP Handshake Create Connection Read Request from Connection Socket Send Request Send Response to Connection Socket Read Response Close Connection Socket Close Socket

38 TCP Client-Server W.X.Y.Z:1234 A.B.C.D:5678 Create & Bind Server Socket port: 1234 Create Socket Wait for Incoming Connection on Server Socket TCP Handshake W.X.Y.Z:1234 A.B.C.D:5678 Create Connection W.X.Y.Z:1234 Read Request from Connection Socket W.X.Y.Z:1234 A.B.C.D:5678 Send Request Send Response to Connection Socket W.X.Y.Z:1234 A.B.C.D:5678 Read Response Close Connection Socket Close Socket

39 TCP Python Client from socket import * servername = A.B.C.D serverport = 1234 clientsocket = socket(af_inet,sock_stream) clientsocket.connect((servername,serverport)) message = input( lowercase sentence: ) clientsocket.send(message) modifiedmessage = clientsocket.recv(2048) print(modifiedmessage) clientsocket.close()

40 TCP Python Server from socket import * serverport = 1234 serversocket = socket(af_inet,sock_stream) serversocket.bind((,serverport)) serversocket.listen(1) print( server ready ) while True: connectionsocket, address = serversocket.accept() message = connectionsocket.recv(2048) modifiedmessage = message.upper() connectionsocket.send(modifiedmessage) connectionsocket.close()

41 TCP Client Server W.X.Y.Z:1234 Create & Bind Server Socket port: 1234 socket, bind, listen A.B.C.D:5678 Create Socket socket Wait for Incoming Connection on Server Socket accept TCP Handshake W.X.Y.Z:1234 A.B.C.D:5678 Create Connection W.X.Y.Z:1234 connect Read Request from Connection Socket recv W.X.Y.Z:1234 A.B.C.D:5678 Send Request send Send Response to Connection Socket send W.X.Y.Z:1234 A.B.C.D:5678 Read Response recv Close Connection Socket close Close Socket close